Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: dsesmg on October 09, 2009, 06:32:57 AM
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Hi, is there any way to convert 24v dc voltage to 12v?
I have a 24v dc power supply and I hope I could utilize this voltage to get 12v dc without having to buy another commercial power supply.
Please help me.
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Although very wasteful, you could use a 12v regulator.
How much current do you intend to pull from the 12v source?
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Hi, how are you?
it is less than 100mA. It is a photo detector.
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Ahh ok, then a 12v regulator like the 7812 will do fine.
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Hi, thanks a lot.
Do I need to put capacitors before input(24v) and output(12v) pin?
According to the datasheet http://www.datasheetcatalog.org/datasheets/150/44435_DS.pdf (http://www.datasheetcatalog.org/datasheets/150/44435_DS.pdf) it seems I don't need extra components.
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Maybe a small cap on the output to smooth things out but it is not necessary...
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Hi,
Yes, you need capacitors on both input and output!
It is very foolish to use a voltage regulator without the caps mounted, almost whatever the load.
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Hi, How are you?
Thank you for your advise.
Then, how much capacitor value should I use in this case?
Is there any fomular to calculate the required value of capacitors?
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The Regulator data sheet usually gives recommend cap values. Different regulators could have different cap values.
In general a 0.1uF ceramic cap on the regulars input and output pins.
One reason for these caps is that if there are long wires the regulate could oscillate.
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Hi,
I'd use 220nF on the input and 22µF on the output - mounted as close to the terminals of the regulator as possible.
waltr <- you don't need long wires for an uncapped regulator to oscillate, just a little bad luck. Even without oscillations, you still want caps to dampen noise.
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Good point Soeren.
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Thank you.